Scientists develop new test to diagnose Brucella canis

Researchers at the Cornell University College of Veterinary Medicine (CVM) have developed a new test to diagnose Brucella canis, a zoonotic disease that can spread to people through contact with infected dogs. The Cornell Animal Health Diagnostic Center (AHDC) is the only lab in the country offering a new test that measures antibodies in dogs directed against Brucella canis antigens — the Canine Brucella Multiplex (CBM) assay.

Dr. Toby Pinn-Woodcock, assistant clinical professor in Veterinary Support Services at CVM says: “We believe that this test is more sensitive and less prone to false-positive results.”

Brucella canis, which affects up to six percent of dogs in the United States, shows a variety of symptoms, from spontaneous abortion to spinal pain, and therefore is difficult to detect. The average time to identify the disease in a dog is about six months, according to a paper co-authored by Pinn-Woodcock and five other Cornell researchers, which was published in the American Journal of Veterinary Research.

The lengthy diagnosis has raised concerns among veterinarians and state health officials because Brucella caniscan spread to humans, causing flu-like symptoms, organ-based complications involving the skeletal system and possible problems with pregnancy.

People who are most at risk for infection are owners of dogs that have the disease, workers at commercial breeding operations or laboratory technicians who culture the organism. The disease is more prevalent among rescued stray dogs or dogs raised at large breeding operations.

Dogs diagnosed with Brucella canis are treated with a combination of antibiotics, often long-term. If treatment is effective, the levels of antibodies directed against the organism are expected to decrease. It is difficult to determine when a dog has been completely cleared of the infection, however, because the pathogen can evade immune detection. The challenges in curing the disease have led many veterinarians who diagnose dogs with Brucella canis to recommend that they be euthanized.

“It can be very hard to completely eliminate from animals because the pathogen essentially lives within the cells,” said Dr. Alexandra Newman, the state public health veterinarian with the New York State Department of Health. “The only way we can guarantee that there will be no risk of human exposure is by euthanizing the dog.”

In New York State, pet owners are allowed to decide whether to euthanize or treat the animal. The first recommendation is to neuter the dog. “Preventing the breeding of infected dogs decreases the likelihood that they will spread the infection,” said Dr. Cassandra Guarino, an assistant professor of practice in the department of Population Medicine and Diagnostic Sciences at CVM.

With the new CBM assay, veterinarians can now monitor how well dogs respond to treatment for the disease. The Cornell research team is seeking funding to conduct a future study that would show whether dogs that have a prolonged drop in antibody levels are cured of the disease. Until further studies are done, Pinn-Woodcock said she wants veterinarians across the country to know that the new test may provide a means of monitoring response to antibiotic treatment in dogs diagnosed with Brucella canis.

The full version of this story appears on the Cornell University College of Veterinary Medicine website.